After screen repair or replacement

Hello. I just want to ask..

after my phone got a display repair or replacement.. it seems that the screen is not oled now and im seeing a lines like a canvas on my screen? If after the fix from the authorized shop. Will they replace it with with a lower end item or counterfeit? I have no trouble since im able to use my phone again.. it just make me curious if this is still oled or a lower end type of screen